What code can I use when doing a root canal on a primary molar?

Answer

If you are performing a root canal on a retained primary molar with no permanent successor tooth—and filling the canals with gutta percha—you can report D3330 endodontic therapy, molar (excluding final restoration).

If there is a permanent successor—and you are doing root canal therapy and placing a resorbable material in the canal(s)—report D3240 pulpal therapy (resorbable filling) - posterior, primary tooth (excluding final restoration).